Do failed tracking markers still contribute to the solution?
All available markers are used when creating a camera tracking solution. Markers that have moved off screen can be cleared of bad tracking data to help improve the solution.

By going to the last good frame and selecting the marker you can use Clean After or go to the first good frame and press Clear Before, you remove the tracking data that is contributing to a bad solution.



This short demo by Sebastion Konig shows how to use the tracking curves to find bad markers.